Speed responsive switch



June 5, I v R VON REPYPERTT SPEED RESPONSIVE SWITCH Filed .Jan. 1, 19432 Sheets-Sheet 1 FIGJ. I 4/ JF- -i VENT OR A TTOHNE Y June 5', 1945.

R VON REPPERT 2,377,830

SPEED RESPONSIVE SWITCH Filed Jan. 1, 1943 2 Sheets-Sheet 2 PalentedJune 5, 1945 v SPEED RESPONSIVE SWITCH Richard Von Reppcrt, Rochester,N. Y., assignor to International Business 'Machines Corporalion, New

York

York, N. Y., a corporation of New Application January 1, 1943, SerialNo. 471,039 2 Claims. (01. zoo-so) This invention relates to typewritingmachines.

The main object of the present invention is to provide an improved speedgoverning device for motive power means of a machine requiring aconstant source of speed power.

Another object of the present invention is to provide an improved speedregulating means for the driving motor of a power operated typewritingmachine or other oflice appliance.

An object is to provid an improved contact controlling device for thespeed governing means of propulsion motors such as are commonly used tooperate typewriters and other off ce appliances.

Other objects of the invention will be pointed out in the followingdescription and claims and illustrated in the accompanying drawings,which disclose, by way of example, the principle of the invention andthe best mode, which has been contemplated, of applying that principle.

In the drawings:

Fig. l is a plan view partly in section.

Fig. 2 is an elevation partly in section.

Fig. 3 is a vertical section on the line 3-3 in Fig. 4 is a verticalsection on the line 4-4 in Fig. 2.

Fig. 5 is a vertical section on the line 55 in his. 2.

Figs. 1 and 2 the reference numeral desighates the stator frame of anelectrical propulsion motor, of the type commonly used in driving ofllcemachines and appliances such as power operated typewriters.

,stantially changing the main features of construction which distinguishthe present invention from the prior art.

- The frame I0 is formed with flat sides 10a and a flange Nb which isconcentric with the shaft l l of the motor. Pressed on this flangeisashield Fig. 6 is a vertical section on the line 8--t in A motor ofthis type is provided on the well known Electromatic typewriter and orguard lllc which is concentric with the shaft ii and may be made ofinsulating material. Se-

to the ends of the blocks [2. The opposite. endsof the blocks 12 aresecured to the sides of the The frame It by means of screws it (Fig. 2).

frame; comprising blocks l2 and plate 1:, supports the control contacts,the speed regulating lever,

and mechanism associated with said lever for controlling the contacts aswill be made clear hereinafter.

The'speed controlling mechanism is divided into two main groups orparts, one of which comprises a "centrifugal force operated mechanismmounted on the main shaft ll, while the other comprises the controllingcontacts and a speed regi ilating lever carried by the frame includingthe blocks 12. The first group of parts consists of a disk 15 (Figs. 2and 3) mounted on the shaft H by means of a hub 15a. Mounted on theouter face of the disk 15 is a U-shaped bracket 18 pivotally supportinga lever ll. One arm of the lever ll extends parallel with shaft H and isconnected by a short link I8 to a weight member i9 in the form of a flatthin block or strip secured to a spring 20, which is clamped to abracket 21 secured to the outer face of the disk T5. In order tocounterbalance the weight of the parts so far described the disk i5 isprovided with counterbalance elements 22 riveted to the outer face ofsaid disk. These elements may be bored, milled, or filed as required tobalance dynamically the assembly including the disk 15.

The other arm of the lever ll extends substan tially at rightangles tothe shaft it into a transverse slot formed in a narrow extension 151: ofthe hub lbs and abuts the left hand end (Fig. 2) or rear end (Fig. 3)'of.a pin 23 sliding in a bore in extension i5?) concentric, withsliaftH. The pin 23 is provided with a head 23c which limits left handmovement (Fig. 2) of the pin 23. When the motor shaft H rotates, theweight: member 19 tends to move' radiallyoutwardly of the shaft ii anextent commensurate with the speed of the shaft according to well knownprinciples. In order-to prevent the weight member is from moving too farwhen the motor is operated near its limit of speed, as determined by thecontrol mechanism, there is provided a stop pin 15c (Figs. 2 and 3). Theassembly including the disk is and parts carried thereby rotates withinthe guard ills of the motor frame 10 as most clearly shown in Fig. 2.The outward movement of the weight member 19 in response to thecentrifugal force created by the rotation of the disk l5 by shaft H iscommunicated to the pin 23 by the link 18 and lever Hjwhereby the pintends to move to the right with reference to Fig. 2 as the speedincreases. This movement of the pin is communicated to a contactmemberll secured to a contact strip 25, the latter being provided withan offset bent-over lug 224: (Fig. 4) on which the contact-member 24 ismounted. The latter comprises a thin, narrow resilient strip ofconducting material provided with a contact element 24a engaging asimilar contact element on an definite position and is prevented fromchatterstrip 25.

When the motor is at rest the contacts 24a are closed and shunt a speedcontrolling resistance which is placed in a suitable part of the motorcircuit, in accordance with well known principles of motor control,according to the type of motor. As the speed increases, a point will bereached where the axial movement of the pin 22 in the extension l5b willbe sumcient to move the head 224 into engagement with contact member 24and separate the contacts 24a thereby opening the shunt for theresistance and reduce the speed of the motor.

Alternatively, if necessary, the lugs 25a, 26a carrying the contacts2.4a. may be reversed so that the movement of the pin 22 closes thecontacts 24a instead of opening them. In order to accomplish this itwill be merely necessary to change the extent of ofiset of the lugs 25a,22a to enable the contact member 24 to be placed in front, that is, tothe left (Fig. 2) of member 26a (Fig. 4).

It will be seen from the foregoing that the head of the pin 22a willtake a definite position for each definite speed necessary to produce amovement of the member i8.

Motors of this type usually operate at speeds which may range from about2800 R. P.' M. to 3800 R. P. M., which requires that the spring 20 bemade relatively stiif and the weight I! light in weight in order toavoid excessive spring tension which would result if heavy weights andsprings were used. By using a relatively stiff spring 20 and a smallweight I! it is possible for the governing mechanism to respond veryquickly to small variations of speed. Thismakes it necessary that thenatural period of vibration'of the elements I! and 20 on bracket 2|shall be well above the period of vibration at the highest speed, itbeing understood, of course, that when the motor is running at itshighest speed it will tend to fluctuate above and below the desiredspeed which will, of course, cause the parts I! and 20 to vibrate on thebracket 2|. 7

Since the head of the pin 22 takes a definite position'for each speedand with a slight increase in speed'wlll move further" to the right(Fig. 2) to open the contacts 24a it is possible; by adjusting themember 24 along the axis of the shaft ll in relation to the head of thepin 22a, to adjust the speed of the motor as desired. For this purposethe contact strips 25, 28 are secured to the face of a member 21 whichconfronts the disk II. The member 21 conveniently may be made of a plateof insulating material and is guided for horizontal movement along theaxis of pin 22 by means of pins l2a on each side of a downward extension21a of the plate 21.

fined between a loose washer 29 and a washer 22 riveted to the end ofthe reduced portion 224. A cupped spring washer 2i interposed between.washer 22 and the shoulder in screw 22 presses plate 21 against washer24 but enables the screw 22 to be turned to adjust plate 21 axially ofshaft ll. Th'us plate 21 always is maintained am a the sheet as theplate rotates.

and plate 21 will move to the right with refer-' ing or vibrating onscrew 22.

The screw 22 is threaded into a cam plate 24 provided with three cams24a (Figs. 5 and 6) which are embossed in the plate to form three camgrooves 24b, the grooves beingarranged concentrically of the stud 22,but so shaped that the counterclockwise ends (Fig. 5) of the grooves areaxially nearer the left hand end (Fig. 6) of the stud 28 than theclockwise ends. The plate 24 is pressed against three round-nosed studs22 radially equidistant from the screw 22 and carried by the plate I 2.The studs 2| are shown in Fig. 5 as projecting into the clockwise endsof the grooves24b and, as viewed in Fig. 5, the grooves leadcounterclockwise and forwardly of the plane of the sheet, or axially ofthe stud 22, whereby, it the plate 24 is rotated clockwise in Fig. 5,the plate 21 will also move rearwardly oi the plane of Thus the stud 22once to Figs. 2 and 6, and tend to move the contact element 24 away fromthe head 22a of the pin 22.

plate 34 clockwise the full extent limited by the lengths of the camgrooves 24!), the pin 22 will have to move virtually to its other limitof travel before actuating the member 24 'sufiiciently to open thecontacts 24a. This, of course, will occur at maximum speed and themaximum centrifugal force exerted on the weight IS.

The plate 24 is rotated by means of a manual setting member or leverconsisting of plate 22 (Figs. 1, 2, 4, and 5) provided with threearcuate slots 22:: through which extend screw studs 2 threaded intothree radially equispaced holes in the plate I 2. The latter has asuitable hole large enough loosely to receive a hub 24c (Figs. 2, 5, and6) fixed to the plate 24 into which hub is threaded the screw 22. Theouter or right hand end (Fig. 2) of the stud 22 is slotted and providedwith a lock nut 22- which may be screwed up against the hub 240 to lockthe stud as against rotation relative to plate 24. Interposed betweenthe disk 22 and the plate II are friction washers 29 which may take theform of simple washers of resilient material such as spring steel orphosphor bronze bent along the diameter and have sumcient friction tohold the plate in any adjusted position.

For the purpose of rotating the plate 24 manually it is provided with anextension 22b (Figs. 1, 2, 4, and 5) having a pointer portion 220 bentat an angle to extension 22b. When the motor is properly installed inthe machine the pointer portion 220 may cooperate with a suitable scaleon the outer frame of the machine and the portion 22b extends through asuitable slot to enable theplate 22 to be moved through an angleapproximately limited by the lentths ,of the slots 22a. For the purposeof holding the plate 24 in contact with the pins 22 there are secured tothe'plate 22, intermediate the ends of the slots 22a, three leaf sprinzs42 (Figs. 2 and 5) which press on the plate 24-near screw 22 and thustend-to press the plate to the right in Figs. 2

and 6 against the studs 22 which are rounded in the edges of plate 34.

' to the motor circuits.

verse section. The plate. is keyed to the plate 36 by means of lugs 36dwhich are bent at right angles to the plate 36 and extendinto slots 34dOwing to the fact that the plate 21 is frictionally mounted on the endof the screw 28, the position of the contact member 2| may be initiallyadjusted relative to the head 23a of stud 23 by loosening the lock nut38 and rotating the screw 28 by means of a screwdriver. This causes theplate 21 to move to right or left (Fig. 2) as the case may be relativeto the plate 34. Thus if the lower limit of speed should be determinedas 2800 R. P. M.,-the stud 28 may be turned until the contacts 24abarely open with the manual setting member 36b in the position of Fig.5. Obviously it would be useless to adjust the contact member 24 to thepoint where the contacts 24a open at somelower speed as they would makeit impossible to obtain the maximum speed allowed by the range ofmovement of plate 38.

In order to avoid the use of soldered connectionswhich might be brokenfrom vibration, the e contact strips 25, 26 are provided with lugs b,28b (Figs. 1 and 4) which extend into slots I 2a (see Fig. 2 also)formed in the plates 12 and extending parallel with the axis of rotationof the motor. The ends or these lugs bear against contact strips 4|secured in the slots l2a and having at their ends resilient portions ato maintain good contact with the lugs 25b, 26b and also with members.42 such as buttons insulatably mounted on the motor frame In andconnected This method of making connections between the governorcontrolled contacts 24a and the motor circuits makes it possible todisassemble the mechanism without unsoldering any connections and alsoprovides a more rugged connection which is noteasily disturbed.

One or the practical advantages or the governor described herein is thatall of the electrical connections and speed regulating parts are whollyenternal of the centrifugal force responsive elements of the system. Inprior art the contacts are mounted on the disk I! requiring thatelectrical connections be made by means of a.

commutator device. These commutator devices not only increase the costof the device .but create a great deal or trouble in service owing todeterioration of the brushes and commutator seg-:-

ments.

While there have been shown and described and pointed out thefundamental novel features of the invention as applied to a singlemodification it will be understood that various omissions andsubstitutions and changes in the form and details of the deviceillustrated and in its operation may be made by those skilled in theart, without departing from the spirit of the invention. It is theintention, therefore, to be limited only as indicated by the scope ofthe following claims. I

What is claimed is:

1. A speed responsive switch for use with retary mechanism having aswitch actuating mem-- ber centrifugally displaced along an axis ofrotation, comprising a support screw disposed axially of said member,manual adjusting means mountin said screw in said frame including amanual member movable to select a speed, a support plate mounted on theend of said screw conmanual adjusting means is operated to select aspeed.

2. A- speed responsive switch for use with rotary mechanism having aswitch actuating member centr'ifugally' displaced along an axis ofrotation, comprising a support plate disposed transversely of andconfronting one end of the actuating member, a second supportplatemounted between said member and the first plate, contact meansmounted on said second plate and including a contact element actuable bysaid member with changes in the motor speed;

and means for mounting said second plate on the 'said first plate formovement axially or said member, including a manually adjusting memberand an adJusting screw bodily movable axially oi the actuating member bysaid adjusting member, said second plate being mounted on the end ofsaid adjusting screw.

l RICHARD VON'REPPERT.

